This invention relates to an automatic typing system which includes a keyboard entering information to by typed, means for recording the entered information, a printing unit operable to print the recorded information and a display device which displays information entered from the entering means. The invention is concerned with the problem of enabling entered information to be amended.
In particular, the present invention relates to a particular device of the system by means of which it becomes very simple to amend a text previously recorded on the recording carrier. In automatic typing systems, the need very frequently arises for amending a text recorded previously both in order to eliminate errors and in order to change the text because of subsequent updatings thereof.
There are numerous automatic typing systems which comprise devices adapted to facilitate the search for the lines of the test to be amended for the purpose of accessing the lines containing an error.
One of these typing systems comprises a selector for selecting the part of the text to be amended on a magnetic tape. By means of the selector, a code associated with the text to be amended is introduced and a search for the text is thereafter commanded by means of a push button. The search for the text is made automatically and when the search has taken place, the typing system positions itself at the first line of the selected part of the text. If the operator wishes to correct an error appearing in the fourth line of the selected part, he actuates an appropriate push button three times and the push button produces the positioning of the system at the beginning of the fourth line. This positioning line by line may be optionally effected simultaneously with the printing of the lines themselves.
When the system is positioned at the beginning of the fourth line, the operator can command the printing word by word of all the words preceding the word which is wrong. At this point, the system is positioned at the word to be corrected, which can thus be altered.
This system, therefore, has the disadvantage of having to proceed line by line as far as the line to be amended and then proceed word by word as far as the word to be corrected. Corrections are, therefore, laborious and require a great amount of time to be carried out.
Another automatic typing system is, moreover, known wherein the search for the line to be altered is rendered faster owing to the fact that on recording of the text on a magnetic carrier it is divided into paragraphs by means of the recording of suitable check signals. When the operator wishes, for example, to correct an error contained in the fourth line of the third paragraph, he first commands the positioning of the system at the beginning of the third paragraph by actuating an appropriate key twice and then commands the positioning at the beginning of the fourth line as hereinbefore described.
This system, therefore, provides for division of the text into paragraphs. This division is effected by the operator in the recording stage by suitably recording two return-to-the-beginning characters at the end of each paragraph. This is made necessary by the fact that a single return-to-the-beginning character identifies the end of each line and, consequently, this character cannot be used singly to identify the end of a paragraph.
During the stage of searching for the successive paragraphs, the system recognizes the end of each paragraph by recognizing the pairs of carriage return characters recorded on the recording carrier. Moreover, the paragraphs are searched for one at a time. That is, if the operator intends to access the third paragraph, he actuates a first time a key which causes the positioning of the system at the first paragraph. Then the operator actuates the key a second time and the system positions itself at the second paragraph and, finally, he actuates the key a third time, positioning at the third paragraph being produced.
This typing system, therefore, has three disadvantages: a first operating disadvantage consists in the fact that, in order to identify the end of a paragraph, the operator must effect the introduction of a command (double return-to-the-beginning) which is usually not employed in typewriters. In fact, the end of a paragraph is normally commanded by means of a single return-to-the beginning command, so that the operator is very frequently made to forget to introduce the second command at the end of the paragraph.
A second operating disadvantage resides in the fact that the operator must wait for the search for each paragraph in order to command the search for the following one.
Another disadvantage is that of providing a suitable circuit for recognizing the double carriage return character during the search for the paragraph itself.
This system, therefore, also has the drawback of having to proceed paragraph by paragraph as far as the desired paragraph and thereafter line by line as far as the line to be amended. In short, this system also proves to be slow and complicated to use.
Finally, there is another typing system wherein the positioning at the beginning of the line to be amended can be commanded without necessarily having to proceed through the preceding lines. In fact, this system enables the beginning of each line to be accessed directly by using the initial word or words of the lines as search keys.
More precisely, if the operator wishes to position himself at the beginning of the line which commences with the word "system", he introduces this word by means of the keyboard and actuates an appropriate key. At this point, the typing system begins the search and stops when it finds the first line which begins with the word "system". Afther this, it proceeds word by word as far as the point to be amended.
Even if this typing system eliminates the disadvantage of having to proceed line by line or paragraph by paragraph as far as the line to be amended, it has the disadvantage of still requiring a further positioning operation starting from the beginning of the line as far as the point to be amended in the line. This disadvantage results from the fact that the text is recorded on the recording carrier already divided into lines, so that access to the various points of the text can take place only line by line.
Moreover, none of the described typing systems includes a visual display for visually displaying the contents of the recording carrier on which the text is recorded as far as the point at which the operator intends to insert the amendment. Such visual display is particularly useful, since it provides the operator with the possibility of scanning a section of the recording carrier as far as the desired point. In short, this visual display represents a "window" by means of which the operator can observe the contents of the recorded text immediately preceding the point at which he wishes to insert an amendment.
Therefore, where an automatic typing system is concerned, there exists the problem of accessing directly in a pre-recorded text the point which it is intended to amend, regardless of whether this point is at the beginning, at the end or in the middle of a line of typescript, and of visually displaying the recorded text as far as the point of insertion of the amendment, without having to apply special operative procedures during the recording of the text for identifying blocks of the text, or use special circuits for recognizing the beginning of the blocks.